Remedial work against the Mexican Cotton - boll Weevil

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Circular No. 33, SecondSeries. (SupplementarytoClrculari18and27.)

United States Department of Agriculture, DIVISION OF ENTOMOLOGY.

REMEDIAL WORK AGAINST THE MEXICAN COTTON-BOLL WEETIL.

In the courseof the investigationsof the boll-weevil problem in southern

Texas

in the spring of 189G

by my

^first assistant, Mr.

C. L. Marlatt, ^it

was

early discovered thatthe overwinteredweevils

were

not only collecting onthe volunteer cottonbut

were

feeding to anoticeable extent on the

expanding

leaves

and

soft green stems of the

new

shoots.

The

possibilityof destroyingthebeetles

by

wetting this

new growth by an

arsenical poison atonce suggesteditself,

and

experiments

which were

promptlyinstitutedwith confined beetleson small plants demonstrated conclusively that not onlydo the beetles feed

on

the leaves

and

tender shoots voraciously,butthat

by

poisoning such shoots thebeetles subjected to experiments could all bekilled inthe course of 8 to 12 hours.

A ^more

^{general experiment to test the value of poisoning}

^was

instituted in a ^field containing

much

volunteer cotton

which had

already (April 26)

made

considerable growth,

forming

ratherdense bushes. This experiment

was

carried out on the

farm

of

Judge

Borden, of Sharpsburg, the plants being sprayed

from an

ordinary

wagon

cart. Greatdifficulty

was

experienced in wetting

more

than the outerleaves,

which were now

of large size

and

protected

much

of the inner growth, especially the squares.

The outcome

of this

work

demonstrated thatwhile the poisoningof the cotton plant

was

thoroughly feasible

and

practicable

when done

at the right season

and would

^resultinthekilling oftheoverwinteredweevils,if delayed too long^it

was

veryunsatisfactory

and

promised very littleofvalue.

In otherwords,it is

much more

difficulttopoison plants successfully as a

means

of destroying theweevil than to poison

them

for the cotton-leaf

worm, which

feedsveryoftenifnot generally

on

theouter leaves

and

can be reached

by powder

dusted over the plant inthe

most

careless

and

general

way. The

weevil, ontheotherhand,feed- ing as itdoes

on

the tender

growing

tips

and on

the flower buds,

which

are veryoften concealed

and

covered

up by

the larger leaves of oldergrowth,requiresforitsdestructionverycareful

and

thorough spraying,suchas

would

beimpossibleafter eithervolunteerorplanted cotton has reached

any

considerable size.

SB

&33

As

ameans, however, of destroying the overwinteredweevils

on

volunteer cotton, a spraying of poisonin April promised very valu- ableresults,

and

a

recommendation

for such treatment

was

inserted in thelast editionofthe boll-weevil circular (Circular No. 18, second

series), asfollows:

Thebeetleswhich have survived thewintercollect intheearlyspringon the

firstsproutswhich appearon old cotton and eatthe partiallyexpanded leaves andthetender leaf stems, andatthis stage can be poisoned bythe application ofanarsenical tothis

new

growth. Todothisitwillbe necessarytothoroughly spray the growingtips, and this should be donewhenvolunteer cottonisvery small, preferablymere sprouts or bunchesof leaves an inch ortwo inlength

;

lateronthe growingparts can not beeasilyreached. With anordinary knap- sack

pump

afield

may

begoneoverrapidlyandthevolunteer cotton thoroughly treated,the nozzle beingdirected ateachgrowingtip. Thefirstapplicationshould bemadeassoonasthe volunteerplants sprout,andperhaps repeatedtwoor three times within as

many

weeks. As ordinarily cultivated, the number of volun- teersissmallandthe time requiredforthethoroughsprayingofsuchplants will not begreat.

A

strongsolutionshould beapplied, viz,1poundofthepoisonto 50 gallons of water, because no harmwill be doneif thevolunteer plants are ultimatelykilledbythe poison.

The

useofpoisons, either

London

purpleorParis green, as described inthe

paragraph

quoted, is thoroughly practicable

and

undoubtedly will be ^of value.

The

careful study, however, of theweevil

dam- age

in

Texas

conducted

by

the Division during the last three or fouryears has demonstrated that the preventionof weevil

damage

is

more

a questionof the adoption of a proper system of cultivation thanof remedial or preventive schemes, suchas the use of poisons.

Inotherwords,it is admitted

by

intelligentplanters

everywhere

that the presence of theweevil is

made

possible

by

a system of culture

which

admitsof the existenceof volunteercotton,

and

ifthe

methods

followed are such as to prevent such volunteer

growth

theweevil will rarelyifever betroublesome.

In ourpublications onthis insect, therefore, great stress has been giventothe cultural

method

of control,

which

isundoubtedlytheone thoroughly effective

means

of avoiding loss

from

the boll weevil.

The

detailsof this

method

arerepeated atthe closeof this circular.

Unfortunately agreat deal ofthe cotton culturein

Texas

is ofthe rather careless sort,

and

there probably

always

will be

more

or less volunteer cottoninfieldsunlessverystringent regulations are passed

and

great careis taken tosee that these are strictlyenforced.

The

poisoning of volunteer cotton in early spring remains, therefore, ^a procedure of importance

and

of considerablepractical utility.

The

present season attention has again been ^directed to this or a very similar

method

of control, in the course⁴ of the investigation of the weevil conditions in Texas by Professor

Townsend,

a field agent of the Division. In the course of this

work

^it

was

discovered that

3

tho weevils

seemed

to

have

a

marked

fondness for sweets, such as molasses,

and would

eat the latter

when

smeared on cotton stalks or

young

shoots eitherwith orwithout an admixture of arsenic.

A

fter eating the poisoned sweets the beetles died within 8 to )l\ hours.

After

some weeks

of experimentation in the field, chiefly at Cuero, Tex., Professor

Townsend recommends and

indorsesveryheartily

two

formulas, one for the treatment of

young

planted cotton

and

the otherfor the destruction oftheoverwinteredbeetlesonthe volunteer.

FORMULA FOR VOLUNTEER COTTON.

The

undiluted molasses is

mixed

with one-fourth its

volume

of arsenic

and

applied to thevolunteer stalks in spring

when

the leaves arebeginning toappear.

The

molasses

must

be kept well stirred to prevent the arsenic

from

settling,

and may

^be

smeared

on the stalks of the volunteer cotton with a stickor brush. All untreated plants

must

be killed

and

onlya

few

poisoned plants should be ^left to the acre. This applies to districts

where

the foliage of the cotton is killedin winter. In

warmer

districts,

where

thefoliageisnot

always

killed inwinter, allbut a

few

of the plants should bekilled

and

up- rooted,

and

the remainder

smeared

with the poisoned molasses, all squares

and

bolls

having

been

removed

toinsure the quickest effect.

Itisbelieved that the weevilswillbeattractedtothesepoisonedplants

by

the molasses

and

willbe killed,

and

thiswillobviate the necessity of treating the

young

plantedcotton.

FORMULA FOR PLANTED COTTON.

White

arsenic (arsenious acid) If ^{to 2} ouncesboiledin agallonof wateruntilthoroughlydissolved;

two

orthreegallonsof thecheapest grade of molasses,

and

one barrel (40 gallons) of water. Stir the molassesinto thewater, then

add

the dissolved arsenic

and mix

the

whole

thoroughly.

Apply

tothe plantwith aforce

pump and

spray nozzle asinspraying for thecotton-leaf

worm.

This mixture is designed for use particularly

on young

cotton plants,

and may

alsobe used for the poisoning of volunteer cotton with a

knapsack

sprayer or larger apparatus, as described in the quotation

from

Circular18.

The

only

advantage

of the sweetened or sirupy

wash

over Paris green,

London

purple, or arsenite of cop- per, as ordinarily used,is in itsbeing supposed toattracttheweevil

;

so that, even althoughthe entire plant

might

notbewetted with the mixture, the weevil

would

be attracted

by

the sweetenedbait tothe parts struck

by

theliquid.

It should be

remembered

that the white arsenic

recommended

is

very caustic

and

is very

much more

apt to

burn

or scaldplants than are the other arsenicalsjust mentioned,

and

itis quite probablethat either

London

purple or arsenite of copper,

which

areof about the

same

costas whitearsenic, will be preferable tothelatter.

The

cheap grade ofmolassesreferred tocan belaid

down

in

Texas

at arate of10 cents per gallon.

White

arsenic costs about 10 cents a

pound

retail,but wholesalecan be obtainedfor

much

less.

London

purple

and

Paris green also cost about 10 cents a

pound

retail.

A

barrel of the mixtureat theprices quoted will cost about 25 cents,

and

should spray

an

acre or

more

of

young

planted cotton.

The much

heavier mixture forvolunteer cotton is used in very limited quantities

and

asmall

amount

will cover alarge area.

The

direc- tions

and

cautionsgiven atthe outsetfor sprayingforthebollweevil are equally applicable to the molasses

and

arsenic

wash

described.

For

field work, however, a large

machine

is necessary, such as the

mounted

horse spray

machines commonly

used for treatment of potato farms.

Itshould be

remembered

thatthistreatment rests merely on

some

preliminary experiments

made

with confined weevils on poisoned plants,

and

its success on alarge scale remainstobe demonstrated.

Its greatest value will come, undoubtedly, in the treatment of vol- unteer plants

and young

planted cotton,

and

its successwith thelat- ter will, undoubtedly, diminish as soon asthe plants

have formed

a

head

or

become

at all bushy. Itis given publicity

by means

of this circular,toget planters to test itfully infield trials,

which

alonewill demonstrateits value or worthlessness.

THE CULTURAL METHOD OF CONTROLLING THE BOLL WEEVIL.

It should be

remembered

that the poisoningof the volunteer

and

alsoof the

young

planted cotton is suggested merelyas a

means

of correcting acondition

which

hasresulted

from

imperfect cultivation,

and

that the great value^of the cultural

method

of control should not belost sightof.

The

description of this

method

given in our last circularon the boll weevil is as follows

:

Thecarefulinvestigation of thisweevil duringthe pasttwoor threeyearsby theDivision of Entomologyhas fullydemonstrated thesupreme importanceof theculturalmethodof control, towhichfact

we

gavespecialprominenceinour

firstcircularon this insect. There can be noquestion

now

that in the proper systemof growing cotton a practicallycomplete remedyfor the weevil exists.

Inthefirstplace, ithasbeenestablished beyond questionthat the conditions of cultivationwhich make volunteer growth possible also

make

the continuance

of theweevil inevitable. Of first importance is the early removal of the old cotton in thefall,preferablyinNovemberorearlier. Thiscan be done bythrow ing out the old plantswitha plow, root and all, and afterwards raking them togetherand burningthem. Thistreatment should befollowed,aspromptlyas

may

be, bydeep plowing, saytoa depthof Cor8inches. This leaves thefield

comparatively clean of old cotton stalks, facilitates thorough cultivation the following year, and, at thesametime, collectsanddestroysall theweevillarvae

andpupaeinthe cottonat the time, andalso mostof the adults. Theescaping beetles will be buried bydeep plowing, and will not again reach the surface.

Few, ifany, of themwill succeedinhibernatingintheabsenceof theordinary rubbishinthefieldsinwhichtheywinter. Fields treated inthis

way

havegiven apracticaldemonstrationof the usefulness of themethod.

Thegreatestdangerfromthe weevilisdueto thepresenceofvolunteercotton, which means earlyfood fortheweevils inthe springand abundant meansfor theiroverwintering, and theeffort made to retainvolunteerand get earlycot- ton, or the "first bale,"is a veryserious menace to cotton culturewithin the weevildistrict.

Thisculturalmethod, ifgenerally practiced, willundoubtedlyprove aperfect remedyforuplandcotton,andwillvastlyreduce weevildamageinthelowlands, wheretheweevil ismoreaptto winter,perhaps inadjoiningwoodsorroadside vegetation. The early removalof cottonbythe means suggestedisespecially advisedwhenever the presence of theweevil shows that the pickingof a top cropisproblematical. Insuchinstancesitwouldbe welltouprootanddestroy cottonstalks inSeptember orOctober, aswould have been thoroughlyfeasible for

much

oftheuplandcottonin 1896. Ifthisculturalmethodcan beenforced, eitherbyState legislation or bythe cooperation and insistence on the partof landowners that their renters shall carry out thesystem outlined, theweevil difficultycanundoubtedlyinverylargemeasurebe overcome.

Inconnectionwith the systemof fall treatment of the cotton, constant and thorough cultivation of the growing cropas lateas possibleisof considerable value, andisalsowhatshould bedoneto insureagood yield. Withacrossbar tobrushthe plants

many

ofthe blossomsandsquarescontaining weevilswillbe jarredtothegroundand buried,togetherwiththose alreadyontheground, in moistsoil, andalarge percentageof the materialwill rot beforethecontained insectshavedeveloped.

Somewhat

^{in line} withthe last

paragraph

is the collection

and

de- struction ofthe infested bolls

and

weevils

from

the plants themselves.

A complex machine

has been devised for this purpose

by

Mr. Stron- hall, of Beeville, Tex. In operation this apparatus passesover one

row

at a time

and

brushes the plants

from

bothdirectionsvigorously

by means

of revolving brushes

working

in opposite directions,

and

the stungbolls

and

squares

which

fallreadily are

caught

onreceiving trays

and

carried to

bags and may

beultimately

burned

or otherwise destroyed.

The machine may

be adjusted toplantsof differentages within certain limits, but

becomes

less effective as the plants get larger.

As

witnessedin operation the presentseason

by

Mr.

Town-

send, ^itproved,

on young

plants, tobe veryeffective

and

satisfactory, collecting alarge percentage of theweevils

and

the stung bolls

and

squares.

The temporary advantage

of the useof this

machine

no doubt will beconsiderable

and may

materially protect the earlycot- ton; itprobablywill notbe of

much

service asa protection for late cotton or the second crop.

L. 0.

Howard, Entomologist.

Approved

:

James Wilson,

Secretary.

Washington,

D.

C, July

1, 1898.

UNIVERSITY OF FLORIDA

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